/Engine/Source/Runtime/Engine/Public/ProfilingDebugging/LevelStreamingProfilingSubsystem.h
Gives child classes an opportunity to track additional data along with the main report. Levels usually progress linearly through the ELevelState values, but may skip values depending on the initial state of the world when tracking begins.
virtual void UpdateTrackingData ( int32 TrackingIndex, [FLevelStats](API\Runtime\Engine\ProfilingDebugging\ULevelStreamingProfilingSubsyste-\FLevelStats) & BaseStats, const [ULevelStreaming](API\Runtime\Engine\Engine\ULevelStreaming) * StreamingLevel, [ELevelState](API\Runtime\Engine\ProfilingDebugging\ULevelStreamingProfilingSubsyste-\ELevelState) PreviousState, [ELevelState](API\Runtime\Engine\ProfilingDebugging\ULevelStreamingProfilingSubsyste-\ELevelState) NewState )